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Canola oil as finish

A few items I sell are kitchen utensils and a few breadboards. I've used a variety of finishes on these including "Salad bowl finish", olive oil, canola oil, and sometimes nothing. I recently was at a housewarming party for a friend and I was chatting with someone there that was a chemist and as we talked about our jobs, she was very interested in the finish I used on these kitchen items. When I told her that I used canola oil, she said that was a BAD idea since canola oil rots wood. I had never heard of this before but I belived her in that she may know something about the chemistry of it all. Does anyone know anything about this?

(post #109339, reply #1 of 32)

Jeffery, seems to me that I have heard the same thing. Canola rings a bell (fire alarm) for some reason. I used to make a lot of cutting boards while practicing joinery and laminating techniques. I was told to never use anything but Mineral Oil. For some reason I can't remember why things like wesson oil, canola oil, peanut oil etc., were bad, just that they were.

(post #109339, reply #4 of 32)

Vegtable oil that are unsaturated are known as drying oils or semidrying oils in the paints and inks industry. It is these points of unsaturationthat are good for you in your salad oil but change over time when exposed to oxygen and become rancid. Used in a varnish, dryers are added which catylize the reaction to make a tough film. My at home reference does not give the make up of the different fatty acids esters that make up rape seed oil so I can't compare it with a drying oil such as linseed. Canola is a name that was invented because they figured that rape seed wouldn't sell. But to rot the wood? I honestly can't see how it could.

(post #109339, reply #6 of 32)

Canola stands for CANada Oil Low Acid, and is a variety of rapeseed that contains less than 2% erucic acid. This improves its safety for food use. All Canola is rapeseed, but not all rapeseed is canola, if you get me.

(post #109339, reply #7 of 32)

Thanks, Rodger. My Merck Index is one of the few references I have available these days and it didn't show erucic acid as a constituant of rapeseed oil. With your post I worked backwards at it and Merck tells me that erucic acid constitutes 40% to50% of rapeseed fatty acids. I can see that it doesn't look like a good human food but looks like it should be useful incorporated into a varnish. I guess that still doesn't make it good for wooden kitchen ware. Thanks, too, for the canola-rapeseed explanation.

(post #109339, reply #9 of 32)

Actually there is a way to seal/treat cutting boards with paraffin--it was used in commercial establishments on their big butcher blocks. Paraffin is food safe--present in some types of candy coatings to make them harden.

The canola oil/anyvegetable/nut oil as a finish is just not good--it will go rancid and get sticky. Mineral oil or nothing is the way to go.

(post #109339, reply #10 of 32)

This has come up many times before in woodworking circles. Canola, olive, safflower, and several other types of oils will turn rancid.

However, almond oil does not turn rancid, and is an excellent choice to finish cutting boards. You don't need anything special, just buy almond oil from the grocery store and wipe it on. Let it soak in, then add another coat or two, wiping off any excess.

By the way, I'm not changing my identity on you, it's just that this new forum suddenly won't accept my password and user name, so I keep having to create new ones. I'm on my third "identity" now!

I've been finishing cutting boards for a couple decades with linseed oil with no problems with rancidity or any reports of sickness; right now, i have a couple dozen left over from my production from last year's shows that are still fine after sitting in the crates for months. I have heard of some cases of sickness/death when industrial mineral oil was used instead of FDA-approved food-safe mineral oil in food prep, though the tiny amount of anything one could put on a board would pretty much eliminate this happening.

Mostly, people worry too much about something that won't matter as soon as the board or utensil is washed the next time. I care a little more because my hands are in the oil for a couple hours at a time in a finishing session. And they don't sell without being oiled first.

(post #109339, reply #12 of 32)

Just recently I read in one of my woodworking magazines (probably FWW) about a great wood utensil treatment. Apparently this recipe came from a wooden spoon manufacturer in West Virginia I believe. I've used it and I think it works pretty well.

Melt 1 part pure beeswax in 5 parts mineral oil. I did this in my microwave in a shallow Pyrex dish. It took about 6 minutes for the wax to melt on 50% power. No bubbling or spattering. I stirred it and let it cool. It works well and smells great! It last just as long as mineral oil (my previous favorite) but is much easier to apply.

(post #109339, reply #20 of 32)

You state Tried & True's marketing hype is the only difference - not so. T&T finishes clearly state no heavy metals, driers, etc. so that you could literally ingest the stuff. Virtually all finishes with few exceptions like T&T do have additives that are harmful in the liquid form. Folks state that once dry, commercial products are not harmful - please provide the testing documentation that verifies that for the various commercial brands. If you've got heavy metal driers in the liquid state, where do they go when it dries - in the air? That doesn't sound good. Maybe they are hermetically sealed for another generation!

(post #109339, reply #21 of 32)

EDGREGG, In the mid 70's the US government decreed that all interior finishes must remove lead and any toxic materials that would remain after the finish was cured. You can request a Material Safety Data Sheet from any manufacturer of an indoor finish and it will describe its non-toxic nature.

Doc, Twice I have been in butcher shops when the guy came in to refinish the butcher blocks. In both cases he applied a mixture of mineral oil and paraffin after he trimmed and flattened the block. The last time was only a couple of years ago and he said he, and his father before him, had used that mixture and he said it was traditional in his trade. At night, the butcher would shake salt on the block claiming it "drew out the liquids." Don't know about that.

(post #109339, reply #22 of 32)

Material Safety Data Sheets are only part of the story - they are developed for folks who handle materials and not necessarily the end product. For example, there MSD sheets for all the components that go into making the plastic case on your radio but not the plastic itself. Other agencies pick the ball up here and in the food/food equipment/food handling industry, the NSF (National Sanitation Foundation) is the non-profit agency that provides this info. Very few finishes are approved by the NSF. I would be very cautious in suggesting to anyone that an indoor finish is OK for contact with food or for ingestion. Many finishes really are not completely hardened (the chemical reactions are still occurring) sometimes for weeks or months depending upon a number of conditions. To use an indoor finish on a food utensil and have a child chew on it a week later could be very dangerous. As a chemist, I've learned to be very cautious even with reagents that I am familiar and have used before. I stand by my statement - unless it has been approved for use with food (NSF approval), don't use it.

(post #109339, reply #24 of 32)

You will note that I have been very careful to qualify my statement about the non-toxic nature of an interior finish to one that was "cured" which I mean, the chemical reaction has for all intents and purposes, stopped. At that point, the government regulations--as I have been told--require that the material could be ingested without harm. Many finishes take weeks to cure. Varnishes whether oil based or waterborne will take up to 4-5 weeks to cure depending on film thickness and temperature/humidity. The newer low VOC requirements are also causing finishes to take longer to cure.

As to the NSF, what wood coating product do they approve? I have been trying to find any government agency that specifically approves the food safe quality of finishes. As far as I have been able to find out, there are none except for food grade shellac which is used on pills and M&M's.

(post #109339, reply #14 of 32)

Hi, Steve. I was responding to Howie's mention of mineral spirits in post #3. Neophytes might not know mineral spirits = paint thinner, so i wanted to wave them off it as a board/utensil finish, if only for the flavor!

(post #109339, reply #19 of 32)

All the oilseeds such as flax (=linseed), rapeseed, soya beans etc. were originally primarily used in industry, while the remaining "oilcake" left after extraction of the various oils was - and is - a valuable protein source for livestock (when steam-pressed, that is - - the solvent-extracted oilcake was a different story) Rapeseed oil was in demand, but the erucic acid gave a bitter taste, making the meal unpalatable for animals, just as the oil was to us humans. The reason canola became so popular was that the residue could now be sold as livestock feed instead of having to pay to have it hauled to the dump. Food safety was never an issue because of the bitter taste, but the "new" oil soon became a food item on the grocery shelf.

True, most of the unsaturated vegetable oils will eventually harden to some extent, but without the addition of metallic salts and other catalysts as in Japan dryer, they will never fully cure, and will remain sticky for a long time, giving the appearance of a finish, but offering very little protection to the wood. And it is usually the uncured oil that turns rancid, not the polymerized finish. Mineral oil will never harden; it may be considered a polish, but not a finish.

I have had some success using walnut oil, applying it hot (not quite smoking) and letting the wood soak up as much as it will take.

The old-time meat cutters almost never applied parafin or other finishes to their butcher-blocks. Even though the blocks were generally make of end-grain rock maple, the cutting and chopping would wear the surface down fast enough that finishing and preservation were not an issue. Most of the time, the block would be rubbed down at the end of the day with a handfull of lard or whatever fat was on hand, not to protect the wood, but to make clean-up the following day easier: Instead of washing and scrubbing, the block could simply be scraped clean with one of the knives.

(post #109339, reply #23 of 32)

FWIW (and since this is anecdotal evidence, I guess it's not worth much) I don't know nuthin' about Canola, but the slide-out bread board that came with our built-in kitchen cabinets included instructions to use peanut oil on it. So, I've used only peanut oil (Planters) since then (8 years ago), and I can't detect any rancidity (is that a word?) on it--or on any of the other cutting boards that I've used it on.

I just did a sniff test on the boards, but I confess, my smell ain't what it used to be, so there you are.

(post #109339, reply #25 of 32)

Sounds like it's worked great for you! I used to use olive oil to oil bridles back in my horse-showing days. One cautionary note -- there are a few people around who are deathly (literally) allergic to peanuts. If you have anyone new over for dinner, hope they aren't one of them. It takes only a miniscule trace of anything peanut to send them into shock.

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)

(post #109339, reply #26 of 32)

The "peanut panic" is hard to ignore since information about it suddenly exploded on the scene a few years ago. A good survey of the situation can be found at Peanut Allergy

It's obviously something to be aware of, and the growing prevalence of atopic dermatitis here in Japan may be connected, but I honestly have never heard of a person here with a specific "peanut" allergy.

(post #109339, reply #27 of 32)

It's obviously something to be aware of, and the growing prevalence of atopic dermatitis here in Japan may be connected, but I honestly have never heard of a person here with a specific "peanut" allergy

Well, believe it. It has nothing to do with a cutting board but we were in Antiqua at a medical conference. A family had brought a teenage baby sitter who had a peanut allergy. They went out to eat--BAD mistake--she had peanuts somehow (don't know how) and over a period of several hours and an airlift to Miami, she died. It is no joking matter to those people. She should have been more careful, but that is no consolation.

(post #109339, reply #28 of 32)

One thing the article I referenced pointed out was the possible connection between "westernized" diet and the peanut allergy. I would have thought that the Japanese diet had more peanut-related items in it, but I'll have to do a bit more searchng about it. Ever since our children were born (18 years), we've seen an alarming increase in the incidence of atopic dermatitis, and many parents are frantically cutting out all sorts of food items (soy, wheat, milk, even rice in some cases) from the diets, but I don't recall "peanuts" being big on the Japanese mind.

(post #109339, reply #29 of 32)

I haven't studied this allergy extensively or anything, but my understanding is that for those who are extremely allergic, it takes such a small amount to produce a reaction that "being careful" can be a serious challenge. Peanut oil is used in a plethora of products; factory machinery may be used to process a food with peanut oil in it, and then subsequently used to process something else (without being cleaned) and trace amounts can end up in the second food. My grandson has a mild allergy to peanuts, and we are being extremely careful with his food, hoping to ensure that it doesn't worsen to be a much worse allergy.

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)

(post #109339, reply #31 of 32)

Slow-drying raw linseed oil, when boiled (hot air blown through it), changes to a quicker-drying oil. This effect can also be achieved and enhanced more easily by the manufacturer with the addition of chemical siccatives, but they are not necessary to create a so-called drying oil---the heat treatment does that by breaking down the oil. Food-safe linseed oil does not have metallic oxide siccatives added.

Howie had a question about NSF-apporved finishes. John Boos cutting board company has NSF-approved boards that are finished with "Mystery Oil", a mixture of mineral, linseed, and tung oil. A google on "food safe linseed oil" yields a bunch of sources for the oil, including T & T.

Peanut oil: i had a renter who was very peanut-aware die of anaphylactic shock after eating a soup in which the peanut taste was undetectable to her. I've recommended peanut oil as one of the oils my customers could use at home, but appreciate the heads up on this since it hadn't occured to me to consider what could happen to their guests. Thanks.